Method We will be sampling along two interrupted belt transects and will be collecting data from all 2 different habitats (Shrubland and hilly grassland). Three samples will be collected from the same habitat at 2 different regions.The site in which we collect our samples will be at least 20m apart to ensure that each population is independent. Also, we will be collecting a sample size of 20 snails randomly at each site to record the types of snails present. To reduce human error, we will establish a standard within our group before sampling on the variables such as snail colour, types, number of bands, size, etc. The results obtained from all sites will be compiled and compared, which will allow us to understand the frequency of polymorphism in the habitat.
Advantages
An interrupted transect allows us to collect data from a range of habitats so that we can compare the contribution ofenvironment to the polymorphism of the snails.
Taking samples from two different transects means that we can compare t he results obtainedfrom the habitats on one transect with the other to see any co-relation, or if the results are due to selection or genetic drift. If selection is the cause, we would expect to see similar results from the same type of habitats on both transects.
Sample size is relatively large to reduce sampling error.
Disadvantages
Time restrictions mean we can only take a total of 6 samples. Thus, our result may not show a true representation of the types of snails present on that particular type of habitat and the statistics we receive may be due to chance.
Null Hypothesis
There will be no difference in the distribution of coloured snails between the different habitats. Explanation: The type of snails present in one type of habitat on one transect may not be present or as dominant on the same type of habitat from the other transect. This might mean that the type of snails present on that habitat is purely due to genetic drift and not due to selection.
Alternative Hypothesis There is a difference in the distribution of coloured snails between the different habitats.
A small frequency of polymorphism will be observed if more than one type of snail is present in the same type of habitat on both transects.
Results:
B
G
O
R
Y
Row Total
Population 1 (Bush)
16
8
6
9
1
40
Population 2 (Grass)
9
10
2
14
5
40
Population 3 (Wood)
17
20
3
0
0
40
Column Total
42
38
11
23
6
120
As some of the results are less than 3; we will combine results of Yellow snails with Green snails and Orange with Red snails.
Therefore, there is a 0.00290591 chance that we would get the results if the null hypothesis is true.
Critical value (2-tailed) = 9.49 Our results are significant as the Chi-square value is greater than the critical value.
Introduction
Capaea nemoralis is a kind of cross hermaphrodites which presents the most polymorphic traits among the European fauna. The theory of polymorphism can be easily explained using snails as they are easy to sample; with distinct features for differentiation of their subtypes since Capaea nemoralis shows difference in shell background colour, number of bands and several other features. Their habitats are small compared to the human population and long-term monitoring can be conducted easily as snails travel about 20metres in their lifetime. The habitat that we sampled from was Pulpit Hill in Buckinghamshire, it has a high abundance of chalk in its soil resulting in a high number of snails due to the fact that snails benefit from chalk to build their shells.
To understand the frequency of polymorphism in the habitat, we set up a sampling regime where we will be sampling along two interrupted belt transects. Data will be collected from 2 different habitats – shrub-land and hilly grassland and samples will be done in triplicates in each habitat at 2 different transects to ensure replication. The site in which we collect our samples will be at least 20m apart to ensure that each population is independent. Also, a sample size of 20 snails will be collected randomly at each site to ensure that our results are significant. To reduce human error, we will establish a standard within our group before sampling on the variables such as snail colour, types, number of bands, size, etc. The results obtained from all sites will be compiled and compared, of which will allow us to understand the frequency of polymorphism in each habitat.
Our proposed hypothesis is that there is a difference in the types of snails between different habitats. A small frequency of polymorphism will be observed if more than one type of snail is present in the same type of habitat on both transects. Thus, our null hypothesis is that there will be no difference in the type of snails between the different habitats. This might mean that the type of snails present on that habitat is purely due to genetic drift and not due to selection.
Method
We will be sampling along two interrupted belt transects and will be collecting data from all 2 different habitats (Shrubland and hilly grassland). Three samples will be collected from the same habitat at 2 different regions.The site in which we collect our samples will be at least 20m apart to ensure that each population is independent. Also, we will be collecting a sample size of 20 snails randomly at each site to record the types of snails present. To reduce human error, we will establish a standard within our group before sampling on the variables such as snail colour, types, number of bands, size, etc. The results obtained from all sites will be compiled and compared, which will allow us to understand the frequency of polymorphism in the habitat.
Advantages
Disadvantages
Null Hypothesis
There will be no difference in the distribution of coloured snails between the different habitats.
Explanation: The type of snails present in one type of habitat on one transect may not be present or as dominant on the same type of habitat from the other transect. This might mean that the type of snails present on that habitat is purely due to genetic drift and not due to selection.
Alternative Hypothesis
There is a difference in the distribution of coloured snails between the different habitats.
A small frequency of polymorphism will be observed if more than one type of snail is present in the same type of habitat on both transects.
Results:
Expected = 14
Chi-sq = 0.286
Expected = 44/3
Chi-sq = 2.189
Expected = 11 1/3
Chi-sq = 1.186
Expected = 14
Chi-sq = 1.786
Expected = 44/3
Chi-sq = 0.007576
Expected = 11 1/3
Chi-sq = 98/51
Expected = 14
Chi-sq = 9/14
Expected = 44/3
Chi-sq = 64/33
Expected = 11 1/3
Chi-sq = 625/102
Degree of Freedom = 4
P-value = 0.00290591
Therefore, there is a 0.00290591 chance that we would get the results if the null hypothesis is true.
Critical value (2-tailed) = 9.49
Our results are significant as the Chi-square value is greater than the critical value.
Introduction
Capaea nemoralis is a kind of cross hermaphrodites which presents the most polymorphic traits among the European fauna. The theory of polymorphism can be easily explained using snails as they are easy to sample; with distinct features for differentiation of their subtypes since Capaea nemoralis shows difference in shell background colour, number of bands and several other features. Their habitats are small compared to the human population and long-term monitoring can be conducted easily as snails travel about 20metres in their lifetime. The habitat that we sampled from was Pulpit Hill in Buckinghamshire, it has a high abundance of chalk in its soil resulting in a high number of snails due to the fact that snails benefit from chalk to build their shells.
To understand the frequency of polymorphism in the habitat, we set up a sampling regime where we will be sampling along two interrupted belt transects. Data will be collected from 2 different habitats – shrub-land and hilly grassland and samples will be done in triplicates in each habitat at 2 different transects to ensure replication. The site in which we collect our samples will be at least 20m apart to ensure that each population is independent. Also, a sample size of 20 snails will be collected randomly at each site to ensure that our results are significant. To reduce human error, we will establish a standard within our group before sampling on the variables such as snail colour, types, number of bands, size, etc. The results obtained from all sites will be compiled and compared, of which will allow us to understand the frequency of polymorphism in each habitat.
Our proposed hypothesis is that there is a difference in the types of snails between different habitats. A small frequency of polymorphism will be observed if more than one type of snail is present in the same type of habitat on both transects. Thus, our null hypothesis is that there will be no difference in the type of snails between the different habitats. This might mean that the type of snails present on that habitat is purely due to genetic drift and not due to selection.